[DebugInfo] Improve handling of clobbered fragments
Summary:
Currently the DbgValueHistorymap only keeps track of clobbered registers
for the last debug value that it has encountered. This could lead to
preceding register-described debug values living on longer in the
location lists than they should. See PR40283 for an example. This
patch does not introduce tracking of multiple registers, but changes
the DbgValueHistoryMap structure to allow for that in a follow-up
patch. This patch is not NFC, as it at least fixes two bugs in
DwarfDebug (both are covered in the new clobbered-fragments.mir test):
* If a debug value was clobbered (its End pointer set), the value would
still be added to OpenRanges, meaning that the succeeding location list
entries could potentially contain stale values.
* If a debug value was clobbered, and there were non-overlapping
fragments that were still live after the clobbering, DwarfDebug would
not create a location list entry starting directly after the
clobbering instruction. This meant that the location list could have
a gap until the next debug value for the variable was encountered.
Before this patch, the history map was represented by <Begin, End>
pairs, where a new pair was created for each new debug value. When
dealing with partially overlapping register-described debug values, such
as in the following example:
DBG_VALUE $reg2, $noreg, !1, !DIExpression(DW_OP_LLVM_fragment, 32, 32)
[...]
DBG_VALUE $reg3, $noreg, !1, !DIExpression(DW_OP_LLVM_fragment, 64, 32)
[...]
$reg2 = insn1
[...]
$reg3 = insn2
the history map would then contain the entries `[<DV1, insn1>, [<DV2, insn2>]`.
This would leave it up to the users of the map to be aware of
the relative order of the instructions, which e.g. could make
DwarfDebug::buildLocationList() needlessly complex. Instead, this patch
makes the history map structure monotonically increasing by dropping the
End pointer, and replacing that with explicit clobbering entries in the
vector. Each debug value has an "end index", which if set, points to the
entry in the vector that ends the debug value. The ending entry can
either be an overlapping debug value, or an instruction which clobbers
the register that the debug value is described by. The ending entry's
instruction can thus either be excluded or included in the debug value's
range. If the end index is not set, the debug value that the entry
introduces is valid until the end of the function.
Changes to test cases:
* DebugInfo/X86/pieces-3.ll: The range of the first DBG_VALUE, which
describes that the fragment (0, 64) is located in RDI, was
incorrectly ended by the clobbering of RAX, which the second
(non-overlapping) DBG_VALUE was described by. With this patch we
get a second entry that only describes RDI after that clobbering.
* DebugInfo/ARM/partial-subreg.ll: This test seems to indiciate a bug
in LiveDebugValues that is caused by it not being aware of fragments.
I have added some comments in the test case about that. Also, before
this patch DwarfDebug would incorrectly include a register-described
debug value from a preceding block in a location list entry.
Reviewers: aprantl, probinson, dblaikie, rnk, bjope
Reviewed By: aprantl
Subscribers: javed.absar, kristof.beyls, jdoerfert, llvm-commits
Tags: #debug-info, #llvm
Differential Revision: https://reviews.llvm.org/D59941
llvm-svn: 358072
diff --git a/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp b/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
index 75a63df..89cd7a8 100644
--- a/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
@@ -1160,7 +1160,9 @@
// Calculate the definition ranges.
for (auto I = Entries.begin(), E = Entries.end(); I != E; ++I) {
const auto &Entry = *I;
- const MachineInstr *DVInst = Entry.getBegin();
+ if (!Entry.isDbgValue())
+ continue;
+ const MachineInstr *DVInst = Entry.getInstr();
assert(DVInst->isDebugValue() && "Invalid History entry");
// FIXME: Find a way to represent constant variables, since they are
// relatively common.
@@ -1215,21 +1217,15 @@
}
// Compute the label range.
- const MCSymbol *Begin = getLabelBeforeInsn(Entry.getBegin());
- const MCSymbol *End = getLabelAfterInsn(Entry.getEnd());
- if (!End) {
- // This range is valid until the next overlapping bitpiece. In the
- // common case, ranges will not be bitpieces, so they will overlap.
- auto J = std::next(I);
- const DIExpression *DIExpr = DVInst->getDebugExpression();
- while (J != E &&
- !DIExpr->fragmentsOverlap(J->getBegin()->getDebugExpression()))
- ++J;
- if (J != E)
- End = getLabelBeforeInsn(J->getBegin());
- else
- End = Asm->getFunctionEnd();
- }
+ const MCSymbol *Begin = getLabelBeforeInsn(Entry.getInstr());
+ const MCSymbol *End;
+ if (Entry.getEndIndex() != DbgValueHistoryMap::NoEntry) {
+ auto &EndingEntry = Entries[Entry.getEndIndex()];
+ End = EndingEntry.isDbgValue()
+ ? getLabelBeforeInsn(EndingEntry.getInstr())
+ : getLabelAfterInsn(EndingEntry.getInstr());
+ } else
+ End = Asm->getFunctionEnd();
// If the last range end is our begin, just extend the last range.
// Otherwise make a new range.
diff --git a/llvm/lib/CodeGen/AsmPrinter/DbgEntityHistoryCalculator.cpp b/llvm/lib/CodeGen/AsmPrinter/DbgEntityHistoryCalculator.cpp
index 618fee9..5dec591 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DbgEntityHistoryCalculator.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DbgEntityHistoryCalculator.cpp
@@ -9,6 +9,7 @@
#include "llvm/CodeGen/DbgEntityHistoryCalculator.h"
#include "llvm/ADT/BitVector.h"
#include "llvm/ADT/STLExtras.h"
+#include "llvm/ADT/SmallSet.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/CodeGen/MachineBasicBlock.h"
#include "llvm/CodeGen/MachineFunction.h"
@@ -30,6 +31,10 @@
#define DEBUG_TYPE "dwarfdebug"
+namespace {
+using EntryIndex = DbgValueHistoryMap::EntryIndex;
+}
+
// If @MI is a DBG_VALUE with debug value described by a
// defined register, returns the number of this register.
// In the other case, returns 0.
@@ -41,33 +46,39 @@
return MI.getOperand(0).isReg() ? MI.getOperand(0).getReg() : 0;
}
-void DbgValueHistoryMap::startEntry(InlinedEntity Var, const MachineInstr &MI) {
+bool DbgValueHistoryMap::startDbgValue(InlinedEntity Var,
+ const MachineInstr &MI,
+ EntryIndex &NewIndex) {
// Instruction range should start with a DBG_VALUE instruction for the
// variable.
assert(MI.isDebugValue() && "not a DBG_VALUE");
auto &Entries = VarEntries[Var];
- if (!Entries.empty() && !Entries.back().isClosed() &&
- Entries.back().getBegin()->isIdenticalTo(MI)) {
+ if (!Entries.empty() && Entries.back().isDbgValue() &&
+ !Entries.back().isClosed() &&
+ Entries.back().getInstr()->isIdenticalTo(MI)) {
LLVM_DEBUG(dbgs() << "Coalescing identical DBG_VALUE entries:\n"
- << "\t" << Entries.back().getBegin() << "\t" << MI
+ << "\t" << Entries.back().getInstr() << "\t" << MI
<< "\n");
- return;
+ return false;
}
- Entries.emplace_back(&MI);
+ Entries.emplace_back(&MI, Entry::DbgValue);
+ NewIndex = Entries.size() - 1;
+ return true;
}
-void DbgValueHistoryMap::endEntry(InlinedEntity Var, const MachineInstr &MI) {
+EntryIndex DbgValueHistoryMap::startClobber(InlinedEntity Var,
+ const MachineInstr &MI) {
auto &Entries = VarEntries[Var];
- assert(!Entries.empty() && "No range exists for variable!");
- Entries.back().endEntry(MI);
+ Entries.emplace_back(&MI, Entry::Clobber);
+ return Entries.size() - 1;
}
-void DbgValueHistoryMap::Entry::endEntry(const MachineInstr &MI) {
+void DbgValueHistoryMap::Entry::endEntry(EntryIndex Index) {
// For now, instruction ranges are not allowed to cross basic block
// boundaries.
- assert(Begin->getParent() == MI.getParent());
- assert(!isClosed() && "Range is already closed!");
- End = &MI;
+ assert(isDbgValue() && "Setting end index for non-debug value");
+ assert(!isClosed() && "End index has already been set");
+ EndIndex = Index;
}
unsigned DbgValueHistoryMap::getRegisterForVar(InlinedEntity Var) const {
@@ -77,7 +88,9 @@
const auto &Entries = I->second;
if (Entries.empty() || Entries.back().isClosed())
return 0;
- return isDescribedByReg(*Entries.back().getBegin());
+ if (Entries.back().isClobber())
+ return 0;
+ return isDescribedByReg(*Entries.back().getInstr());
}
void DbgLabelInstrMap::addInstr(InlinedEntity Label, const MachineInstr &MI) {
@@ -91,6 +104,12 @@
using InlinedEntity = DbgValueHistoryMap::InlinedEntity;
using RegDescribedVarsMap = std::map<unsigned, SmallVector<InlinedEntity, 1>>;
+// Keeps track of the debug value entries that are currently live for each
+// inlined entity. As the history map entries are stored in a SmallVector, they
+// may be moved at insertion of new entries, so store indices rather than
+// pointers.
+using DbgValueEntriesMap = std::map<InlinedEntity, SmallSet<EntryIndex, 1>>;
+
} // end anonymous namespace
// Claim that @Var is not described by @RegNo anymore.
@@ -116,16 +135,67 @@
VarSet.push_back(Var);
}
+static void clobberRegEntries(InlinedEntity Var, unsigned RegNo,
+ const MachineInstr &ClobberingInstr,
+ DbgValueEntriesMap &LiveEntries,
+ DbgValueHistoryMap &HistMap) {
+ EntryIndex ClobberIndex = HistMap.startClobber(Var, ClobberingInstr);
+
+ // TODO: Close all preceding live entries that are clobbered by this
+ // instruction.
+ EntryIndex ValueIndex = ClobberIndex - 1;
+ auto &ValueEntry = HistMap.getEntry(Var, ValueIndex);
+ ValueEntry.endEntry(ClobberIndex);
+ LiveEntries[Var].erase(ValueIndex);
+}
+
+/// Add a new debug value for \p Var. Closes all overlapping debug values.
+static void handleNewDebugValue(InlinedEntity Var, const MachineInstr &DV,
+ RegDescribedVarsMap &RegVars,
+ DbgValueEntriesMap &LiveEntries,
+ DbgValueHistoryMap &HistMap) {
+ // TODO: We should track all registers which this variable is currently
+ // described by.
+
+ if (unsigned PrevReg = HistMap.getRegisterForVar(Var))
+ dropRegDescribedVar(RegVars, PrevReg, Var);
+
+ EntryIndex NewIndex;
+ if (HistMap.startDbgValue(Var, DV, NewIndex)) {
+ // If we have created a new debug value entry, close all preceding
+ // live entries that overlap.
+ SmallVector<EntryIndex, 4> IndicesToErase;
+ const DIExpression *DIExpr = DV.getDebugExpression();
+ for (auto Index : LiveEntries[Var]) {
+ auto &Entry = HistMap.getEntry(Var, Index);
+ assert(Entry.isDbgValue() && "Not a DBG_VALUE in LiveEntries");
+ const MachineInstr &DV = *Entry.getInstr();
+ if (DIExpr->fragmentsOverlap(DV.getDebugExpression())) {
+ IndicesToErase.push_back(Index);
+ Entry.endEntry(NewIndex);
+ }
+ }
+ // Drop all entries that have ended, and mark the new entry as live.
+ for (auto Index : IndicesToErase)
+ LiveEntries[Var].erase(Index);
+ LiveEntries[Var].insert(NewIndex);
+ }
+
+ if (unsigned NewReg = isDescribedByReg(DV))
+ addRegDescribedVar(RegVars, NewReg, Var);
+}
+
// Terminate the location range for variables described by register at
// @I by inserting @ClobberingInstr to their history.
static void clobberRegisterUses(RegDescribedVarsMap &RegVars,
RegDescribedVarsMap::iterator I,
DbgValueHistoryMap &HistMap,
+ DbgValueEntriesMap &LiveEntries,
const MachineInstr &ClobberingInstr) {
// Iterate over all variables described by this register and add this
// instruction to their history, clobbering it.
for (const auto &Var : I->second)
- HistMap.endEntry(Var, ClobberingInstr);
+ clobberRegEntries(Var, I->first, ClobberingInstr, LiveEntries, HistMap);
RegVars.erase(I);
}
@@ -133,11 +203,12 @@
// @RegNo by inserting @ClobberingInstr to their history.
static void clobberRegisterUses(RegDescribedVarsMap &RegVars, unsigned RegNo,
DbgValueHistoryMap &HistMap,
+ DbgValueEntriesMap &LiveEntries,
const MachineInstr &ClobberingInstr) {
const auto &I = RegVars.find(RegNo);
if (I == RegVars.end())
return;
- clobberRegisterUses(RegVars, I, HistMap, ClobberingInstr);
+ clobberRegisterUses(RegVars, I, HistMap, LiveEntries, ClobberingInstr);
}
// Returns the first instruction in @MBB which corresponds to
@@ -204,6 +275,7 @@
const TargetLowering *TLI = MF->getSubtarget().getTargetLowering();
unsigned SP = TLI->getStackPointerRegisterToSaveRestore();
RegDescribedVarsMap RegVars;
+ DbgValueEntriesMap LiveEntries;
for (const auto &MBB : *MF) {
for (const auto &MI : MBB) {
if (!MI.isDebugInstr()) {
@@ -218,14 +290,15 @@
// If this is a virtual register, only clobber it since it doesn't
// have aliases.
if (TRI->isVirtualRegister(MO.getReg()))
- clobberRegisterUses(RegVars, MO.getReg(), DbgValues, MI);
+ clobberRegisterUses(RegVars, MO.getReg(), DbgValues, LiveEntries,
+ MI);
// If this is a register def operand, it may end a debug value
// range.
else {
for (MCRegAliasIterator AI(MO.getReg(), TRI, true); AI.isValid();
++AI)
if (ChangingRegs.test(*AI))
- clobberRegisterUses(RegVars, *AI, DbgValues, MI);
+ clobberRegisterUses(RegVars, *AI, DbgValues, LiveEntries, MI);
}
} else if (MO.isRegMask()) {
// If this is a register mask operand, clobber all debug values in
@@ -234,7 +307,7 @@
// Don't consider SP to be clobbered by register masks.
if (unsigned(I) != SP && TRI->isPhysicalRegister(I) &&
MO.clobbersPhysReg(I)) {
- clobberRegisterUses(RegVars, I, DbgValues, MI);
+ clobberRegisterUses(RegVars, I, DbgValues, LiveEntries, MI);
}
}
}
@@ -252,13 +325,7 @@
"Expected inlined-at fields to agree");
InlinedEntity Var(RawVar, MI.getDebugLoc()->getInlinedAt());
- if (unsigned PrevReg = DbgValues.getRegisterForVar(Var))
- dropRegDescribedVar(RegVars, PrevReg, Var);
-
- DbgValues.startEntry(Var, MI);
-
- if (unsigned NewReg = isDescribedByReg(MI))
- addRegDescribedVar(RegVars, NewReg, Var);
+ handleNewDebugValue(Var, MI, RegVars, LiveEntries, DbgValues);
} else if (MI.isDebugLabel()) {
assert(MI.getNumOperands() == 1 && "Invalid DBG_LABEL instruction!");
const DILabel *RawLabel = MI.getDebugLabel();
@@ -280,7 +347,8 @@
auto CurElem = I++; // CurElem can be erased below.
if (TRI->isVirtualRegister(CurElem->first) ||
ChangingRegs.test(CurElem->first))
- clobberRegisterUses(RegVars, CurElem, DbgValues, MBB.back());
+ clobberRegisterUses(RegVars, CurElem, DbgValues, LiveEntries,
+ MBB.back());
}
}
}
@@ -306,10 +374,20 @@
dbgs() << " --\n";
- for (const auto &Entry : Entries) {
- dbgs() << " Begin: " << *Entry.getBegin();
- if (Entry.getEnd())
- dbgs() << " End : " << *Entry.getEnd();
+ for (const auto &E : enumerate(Entries)) {
+ const auto &Entry = E.value();
+ dbgs() << " Entry[" << E.index() << "]: ";
+ if (Entry.isDbgValue())
+ dbgs() << "Debug value\n";
+ else
+ dbgs() << "Clobber\n";
+ dbgs() << " Instr: " << *Entry.getInstr();
+ if (Entry.isDbgValue()) {
+ if (Entry.getEndIndex() == NoEntry)
+ dbgs() << " - Valid until end of function\n";
+ else
+ dbgs() << " - Closed by Entry[" << Entry.getEndIndex() << "]\n";
+ }
dbgs() << "\n";
}
}
diff --git a/llvm/lib/CodeGen/AsmPrinter/DebugHandlerBase.cpp b/llvm/lib/CodeGen/AsmPrinter/DebugHandlerBase.cpp
index 00e4cea..f24dbf1 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DebugHandlerBase.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DebugHandlerBase.cpp
@@ -229,31 +229,35 @@
// However, we currently do not emit debug values for constant arguments
// directly at the start of the function, so this code is still useful.
const DILocalVariable *DIVar =
- Entries.front().getBegin()->getDebugVariable();
+ Entries.front().getInstr()->getDebugVariable();
if (DIVar->isParameter() &&
getDISubprogram(DIVar->getScope())->describes(&MF->getFunction())) {
- if (!IsDescribedByReg(Entries.front().getBegin()))
- LabelsBeforeInsn[Entries.front().getBegin()] = Asm->getFunctionBegin();
- if (Entries.front().getBegin()->getDebugExpression()->isFragment()) {
+ if (!IsDescribedByReg(Entries.front().getInstr()))
+ LabelsBeforeInsn[Entries.front().getInstr()] = Asm->getFunctionBegin();
+ if (Entries.front().getInstr()->getDebugExpression()->isFragment()) {
// Mark all non-overlapping initial fragments.
for (auto I = Entries.begin(); I != Entries.end(); ++I) {
- const DIExpression *Fragment = I->getBegin()->getDebugExpression();
+ if (!I->isDbgValue())
+ continue;
+ const DIExpression *Fragment = I->getInstr()->getDebugExpression();
if (std::any_of(Entries.begin(), I,
[&](DbgValueHistoryMap::Entry Pred) {
- return Fragment->fragmentsOverlap(
- Pred.getBegin()->getDebugExpression());
+ return Pred.isDbgValue() &&
+ Fragment->fragmentsOverlap(
+ Pred.getInstr()->getDebugExpression());
}))
break;
- if (!IsDescribedByReg(I->getBegin()))
- LabelsBeforeInsn[I->getBegin()] = Asm->getFunctionBegin();
+ if (!IsDescribedByReg(I->getInstr()))
+ LabelsBeforeInsn[I->getInstr()] = Asm->getFunctionBegin();
}
}
}
for (const auto &Entry : Entries) {
- requestLabelBeforeInsn(Entry.getBegin());
- if (Entry.getEnd())
- requestLabelAfterInsn(Entry.getEnd());
+ if (Entry.isDbgValue())
+ requestLabelBeforeInsn(Entry.getInstr());
+ else
+ requestLabelAfterInsn(Entry.getInstr());
}
}
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
index 07232b5..c0b0d0c 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
@@ -1095,67 +1095,92 @@
}
/// Build the location list for all DBG_VALUEs in the function that
-/// describe the same variable. If the ranges of several independent
-/// fragments of the same variable overlap partially, split them up and
-/// combine the ranges. The resulting DebugLocEntries are will have
+/// describe the same variable. The resulting DebugLocEntries will have
/// strict monotonically increasing begin addresses and will never
/// overlap.
//
+// See the definition of DbgValueHistoryMap::Entry for an explanation of the
+// different kinds of history map entries. One thing to be aware of is that if
+// a debug value is ended by another entry (rather than being valid until the
+// end of the function), that entry's instruction may or may not be included in
+// the range, depending on if the entry is a clobbering entry (it has an
+// instruction that clobbers one or more preceding locations), or if it is an
+// (overlapping) debug value entry. This distinction can be seen in the example
+// below. The first debug value is ended by the clobbering entry 2, and the
+// second and third debug values are ended by the overlapping debug value entry
+// 4.
+//
// Input:
//
-// Ranges History [var, loc, fragment ofs size]
-// 0 | [x, (reg0, fragment 0, 32)]
-// 1 | | [x, (reg1, fragment 32, 32)] <- IsFragmentOfPrevEntry
-// 2 | | ...
-// 3 | [clobber reg0]
-// 4 [x, (mem, fragment 0, 64)] <- overlapping with both previous fragments of
-// x.
+// History map entries [type, end index, mi]
//
-// Output:
+// 0 | [DbgValue, 2, DBG_VALUE $reg0, [...] (fragment 0, 32)]
+// 1 | | [DbgValue, 4, DBG_VALUE $reg1, [...] (fragment 32, 32)]
+// 2 | | [Clobber, $reg0 = [...], -, -]
+// 3 | | [DbgValue, 4, DBG_VALUE 123, [...] (fragment 64, 32)]
+// 4 [DbgValue, ~0, DBG_VALUE @g, [...] (fragment 0, 96)]
//
-// [0-1] [x, (reg0, fragment 0, 32)]
-// [1-3] [x, (reg0, fragment 0, 32), (reg1, fragment 32, 32)]
-// [3-4] [x, (reg1, fragment 32, 32)]
-// [4- ] [x, (mem, fragment 0, 64)]
+// Output [start, end) [Value...]:
+//
+// [0-1) [(reg0, fragment 0, 32)]
+// [1-3) [(reg0, fragment 0, 32), (reg1, fragment 32, 32)]
+// [3-4) [(reg1, fragment 32, 32), (123, fragment 64, 32)]
+// [4-) [(@g, fragment 0, 96)]
void DwarfDebug::buildLocationList(SmallVectorImpl<DebugLocEntry> &DebugLoc,
const DbgValueHistoryMap::Entries &Entries) {
- SmallVector<DebugLocEntry::Value, 4> OpenRanges;
+ using OpenRange =
+ std::pair<DbgValueHistoryMap::EntryIndex, DebugLocEntry::Value>;
+ SmallVector<OpenRange, 4> OpenRanges;
- for (auto EI = Entries.begin(), EE = Entries.end(); EI != EE; ++EI) {
- const MachineInstr *Begin = EI->getBegin();
- const MachineInstr *End = EI->getEnd();
- assert(Begin->isDebugValue() && "Invalid History entry");
+ for (auto EB = Entries.begin(), EI = EB, EE = Entries.end(); EI != EE; ++EI) {
+ const MachineInstr *Instr = EI->getInstr();
- // Check if a variable is inaccessible in this range.
- if (Begin->getNumOperands() > 1 &&
- Begin->getOperand(0).isReg() && !Begin->getOperand(0).getReg()) {
- OpenRanges.clear();
- continue;
+ if (EI->isDbgValue()) {
+ // Check if a variable is inaccessible in this range.
+ // TODO: This should only truncate open ranges that are overlapping.
+ if (Instr->getNumOperands() > 1 &&
+ Instr->getOperand(0).isReg() && !Instr->getOperand(0).getReg()) {
+ OpenRanges.clear();
+ continue;
+ }
}
- // If this debug value overlaps with any open ranges, truncate them.
- const DIExpression *DIExpr = Begin->getDebugExpression();
- auto Last = remove_if(OpenRanges, [&](DebugLocEntry::Value R) {
- return DIExpr->fragmentsOverlap(R.getExpression());
- });
+ // Remove all values that are no longer live.
+ size_t Index = std::distance(EB, EI);
+ auto Last =
+ remove_if(OpenRanges, [&](OpenRange &R) { return R.first <= Index; });
OpenRanges.erase(Last, OpenRanges.end());
- const MCSymbol *StartLabel = getLabelBeforeInsn(Begin);
- assert(StartLabel && "Forgot label before DBG_VALUE starting a range!");
+ // If we are dealing with a clobbering entry, this iteration will result in
+ // a location list entry starting after the clobbering instruction.
+ const MCSymbol *StartLabel =
+ EI->isClobber() ? getLabelAfterInsn(Instr) : getLabelBeforeInsn(Instr);
+ assert(StartLabel &&
+ "Forgot label before/after instruction starting a range!");
const MCSymbol *EndLabel;
- if (End != nullptr)
- EndLabel = getLabelAfterInsn(End);
- else if (std::next(EI) == Entries.end())
+ if (std::next(EI) == Entries.end())
EndLabel = Asm->getFunctionEnd();
+ else if (std::next(EI)->isClobber())
+ EndLabel = getLabelAfterInsn(std::next(EI)->getInstr());
else
- EndLabel = getLabelBeforeInsn(std::next(EI)->getBegin());
+ EndLabel = getLabelBeforeInsn(std::next(EI)->getInstr());
assert(EndLabel && "Forgot label after instruction ending a range!");
- LLVM_DEBUG(dbgs() << "DotDebugLoc: " << *Begin << "\n");
+ if (EI->isDbgValue())
+ LLVM_DEBUG(dbgs() << "DotDebugLoc: " << *Instr << "\n");
- auto Value = getDebugLocValue(Begin);
- OpenRanges.push_back(Value);
+ // If this history map entry has a debug value, add that to the list of
+ // open ranges.
+ if (EI->isDbgValue()) {
+ auto Value = getDebugLocValue(Instr);
+ OpenRanges.emplace_back(EI->getEndIndex(), Value);
+ }
+
+ // Location list entries with empty location descriptions are redundant
+ // information in DWARF, so do not emit those.
+ if (OpenRanges.empty())
+ continue;
// Omit entries with empty ranges as they do not have any effect in DWARF.
if (StartLabel == EndLabel) {
@@ -1163,7 +1188,10 @@
continue;
}
- DebugLoc.emplace_back(StartLabel, EndLabel, OpenRanges);
+ SmallVector<DebugLocEntry::Value, 4> Values;
+ for (auto &R : OpenRanges)
+ Values.push_back(R.second);
+ DebugLoc.emplace_back(StartLabel, EndLabel, Values);
// Attempt to coalesce the ranges of two otherwise identical
// DebugLocEntries.
@@ -1292,15 +1320,23 @@
DbgVariable *RegVar = cast<DbgVariable>(createConcreteEntity(TheCU,
*Scope, LocalVar, IV.second));
- const MachineInstr *MInsn = HistoryMapEntries.front().getBegin();
+ const MachineInstr *MInsn = HistoryMapEntries.front().getInstr();
assert(MInsn->isDebugValue() && "History must begin with debug value");
// Check if there is a single DBG_VALUE, valid throughout the var's scope.
- if (HistoryMapEntries.size() == 1 &&
- validThroughout(LScopes, MInsn, HistoryMapEntries.front().getEnd())) {
- RegVar->initializeDbgValue(MInsn);
- continue;
+ // If the history map contains a single debug value, there may be an
+ // additional entry which clobbers the debug value.
+ bool SingleValueWithClobber =
+ HistoryMapEntries.size() == 2 && HistoryMapEntries[1].isClobber();
+ if (HistoryMapEntries.size() == 1 || SingleValueWithClobber) {
+ const auto *End =
+ SingleValueWithClobber ? HistoryMapEntries[1].getInstr() : nullptr;
+ if (validThroughout(LScopes, MInsn, End)) {
+ RegVar->initializeDbgValue(MInsn);
+ continue;
+ }
}
+
// Do not emit location lists if .debug_loc secton is disabled.
if (!useLocSection())
continue;